1. Field of the Invention
This invention relates generally to removable manhole covers and related structures, and more specifically to an improved manhole cover article and its method of manufacture.
2. Description of the Prior Art
Manhole covers are well known, and are typically used as removable access covers or hatches to underground equipment, utility vaults or shafts. Manhole covers are generally supported only at their peripheral edge by a cover frame or ring, and are preferably round (disc-like) in shape (to prevent the cover from falling through the ring). Traditionally, manhole covers have been manufactured from steel or other strong, rigid materials, chiefly so that they will be able to withstand the significant loads that may be applied to their top surface after installation (e.g., vehicular traffic). However, manhole covers made from such materials are necessarily very heavy, and therefore not easily manipulated and removed for user access to the covered volume.